Faraday’s First Law of Electrolysis

 Faraday’s First Law of Electrolysis

Definition

Faraday’s First Law of Electrolysis states that the mass (m) of a substance deposited or liberated at an electrode is directly proportional to the quantity of electricity (Q) passed through the electrolyte.

Explanation

When a direct current flows through an electrolyte, it causes chemical changes at the electrodes. The amount of material deposited (like a metal) or released (like a gas) depends on how much charge is passed. The more current or time, the more substance is produced.

This law is foundational for processes like electroplating, refining metals, and producing gases in labs.

Formula

m = ZIt

Where:

• m = mass of substance (g)

• Z = electrochemical equivalent (g/C)

• I = current (A)

• t = time (s)

Also, since Q = It, the formula becomes:

m = ZQ

Key Points

• Directly links electricity to mass of product

• Z (electrochemical equivalent) is constant for each substance

• Works with both molten and aqueous electrolytes

• Used to calculate yields in electroplating and gas collection

Examples

• Electroplating silver onto jewellery

• Depositing copper during refining

• Collecting hydrogen gas from water electrolysis

Applications / Relevance

• ⚡ Predicting product quantities in electrochemical industries

• 💍 Precision in metal coating

• ⚗️ Laboratory preparation of gases

• 📏 Quality control in manufacturing processes

Question

If more current is passed for a longer time, what happens to the mass deposited?

Answer:

The mass increases, because the mass is directly proportional to current and time (m = ZIt).